Production and isolation of alkali salts of aromatic sulphonic acids



. Patented Dec. 8, 1925.

UNITED STATES PATENT oFFIcE- noun w. HILLYER, or r-Anmmeron, connnc'rrcur, assrono'a TO ru'rmmu.

4 mm v(IKEMIGAI- COMPANY, INC., OF NEW YORK, N. Y., A. COBPOBATTON OF NEW YORK.

PRODUCTION AND ISOLATION Oi ALKALI SALTS OF ABOZJIA'IIC SULPHONIC ACIDS.

Ho Drawing,

'To' all whom it mag concern} "Be it known that I, HoMnn W. HILLYER, a citizen of the United States, residing at Farmington, 5 State of Connecticut, have invented certain new and useful Improvements in the Production and Isolation of Alkali Salts of Aromatic Sul honic Acids; and I do hereby declare the fo owin to be a full, clear, and exact description 0 the invention, such as wi1l"enable others skilled in the art to V which it appertains to make and use the same.

This invention relates to an improved method for the production and isolation of alkali salts of aromatic sulphonic acids, i. e.,-aromatic alkali sulphonates, and more particularly to the production and isolation of such alkali sulphonates from solutions containing calcium salts of the sulphonic acids. y In the sulphonation of aromatic hydrocarbons and their derivatives, as commonly practiced, fit is necessary to use a large exphuric acid, in order that, as the rocess nears completion, andas the water ormed by the reaction-brings about a dilution of the smaller amount of remaining acid, there may nevertheless be .a sufiiciently concens 'trated acid present to carry the sulphonation to substantial completion; Accordingly, when. the sulphonation' process is excess of sulphuric acid 'inzadmixture with thesulphonic acid produced, and it is neces from this phuric acid,'1n order obtain it sarytosslelp'arate the'sulphonic acid K excess in anisolated state.

Various methods proposed for from the excess of sulphuric .aci

- sulphonic acid is diflicultl'y soluble in dilute mineral acid, a simple tiom product ith water may bring about separation ofthe sulphonic acid sothat it can be filtered-out. In certain cases, the ad- 'dition of common salt in solid form or in gphonation is com 5 solution to the diluted sulphonation roduct will bring about precipitation of t 0 free in the county of Hartford,

calcium sulphonate.

cess Of'gfifthGI' concentrated or fuming sul-.

completed, there is present a considerable have heretofore been separatingthe sulphonic acid contained'fjalkali sulphonates, i. e., the alkali salts of in the sulphonation product. When the dilution of the 5 Application 'al'ea January 3, 1920. Serial No. 349,239.

still strongly acid solution. Both of these procedures, however, have the disadvantage that they require the handling and filtration of acid liquors.

It has also been pro osed to neutralize the excess sulphuric 'aci after dilution with water, byv the addition'of lime or calcium carbonate, with resulting production of a neutral soluble calcium salt of the sulphonic acid, and conversion of the sulphuric acid into insoluble calcium sulphate which is filtered off from the solution of the soluble ment of the calcium salt solutions it has been proposed to add sodium carbonate for the urpose of precipitating the calcium as calcium carbonate and converting the calcium sulphonate into the sodium sulphonate -which stays in solution. Tliis, solution after filtration from the calcium carbonate, 1s then evaporated-to dryness to obtain the solid sodium salt, or it'may be treated by the addition of common salt in suflicient amount to cause salting out or precipitation of the sodium sulphonate. This procedure hasthe disadvantage and objection of requiring the use of sodium carbonate for the conversion of the calcium sulphonate intosodium' sulphofiate, and filtration of the precipitated calcium carbonate from the sodium sulphonate solution before this solution can be further treated for the recovery of the sodium sulphonate therefrom.

According to the resentinvention, such ob ect1ons and disa vantages are avoided, andthe are directly roduced from the calcium sodium .or'othe'r alkali sulphonates In the further treat- 'sulphonate soutions, as hereinafter more y set'forth. The process of the present invention i s of more cationf'to the produ or less general applition and isolation of honic acids of aromatic hydrocarbons ment s, such'as nit-ration,

hunc acid represenoe of the excess of maining at the end of the phonationyand where such sulphonic acids production and isolation phuric acid neutralized with lime or limestone, with resulting production of the soluble calcium salt of the sulphonic acid, and the reci itation of the excess sulphuric acid as t e d illicultly soluble calcium sulphate which is then removed from the calcium salt solutionby filtration or otherwise. The calcium sulphonate solution is then treated -with common salt or other alkali chloride in suflicient amount to bring about the conversion of the calcium sulphonate into the corresponding sodium or' other alkali sulphonate and precipitation or crystallization of the alkali sulp onate thus produced, so that it can be recovered directly in a solid state, from the calcium salt solution, by a combined operation of double decomposition, and of salting out of the alkali sul i10- nate so formed. The common salt (so ium chloride) or other alkali chloride may be added in its solid form or in solution, and in sufiicient amount for bringing about the desired reaction and precipitation or crystallization. By washing the precipitate of al-' kali sulphonate, after filtration, with astrong solution of the alkali chloride, it may be freed from admixed or adhering calcium salt.

Among the advantages presented by the present invention may be mentioned the avoidance of strongly acid solutions which act injuriously upon certain types of apparatus and the use of neutral or nearly neutral solutions of the calcium salt which have no injurious action upon the common types of apparatus, the avoidance of the use of sodium carbonate and the elimination of the filtration of calcium carbonate and of a separate subsequent treatment for recovery of the alkali sulphonate, and the'direct production from ,the calcium sulphonate solution,

"by a single combined operation, of the alkali sulphonate in solid form, which can be recovered by filtration-from the solution containing the calcium chloride, as well as any unchan d calcium sulphonate and unprecipitate alkali sulphonate.

The present invention is also applicable for the, fractional separation of sulphonic acids formin diflicultly soluble sodium salts from those, orming readily soluble sodium salts. Thus certain alkali sulphonates are salted out by adding much less salt than- Y ess of the invention, the production of the sodium salts of the sulphonic acids will usually be the most important, but the invention is also applicable to the production of potassium salts of sulphonic acids, and of ammonium salts of sulphonic acids, where thesesalts are similarly formed and precipitated.

The extent to which the sulphonation product, containing the excess sulphuric acid, is diluted prior to the precipitation of the excess sul huric acid as calcium sulphate, will vary wit the amount of sulphuric acid present and with other conditions,but ordinarily the concentration of the diluted solution should be suchthat thegypsum is best precipitated while at the same time the calcium salt of the sulphonic acid is retained in solution. The diluted, solution is referably and advantageously treated wit sufii cient lime or calcium carbonate to insure the production of a netural or slightly alkaline solution, but the advantages of the invention may nevertheless be secured to a greater or less extent if the neutralization is not complete, and if some small amount of the sulphuric acid remains un-neutralized, provided the degree of acidity is not prej-- udicial to the dsired recovery of the alkali sulphonates. Instead of using lime or calcium carbonate for neutralization of the excess sulphuric. acid, other suitable alkali to, the specific embodiments thereof so illustrated and described. 1. 78 kilos of benzene (C H are added with stirring to 234 kilos of 100% sulphuric acid, and, after adding the benzene, the stirring is continued fol-about 30 minutes ata temperature of about 65 to 70 C. The sulphonation product-thus reduced, and containing the excess sulp uric acid, is then poure into 3000 liters of water and neutral- 1zed with a." slight excess of milk of lime. The excess of sulphuric acid is thereby changed into the difiicultly soluble calcium sul hate which is separated from the neutra solution by filtration. The solution contains the benzene sulphonic acid as the calcium salt. This solution is evaporated to somewhat less than one-third. its volume.

diluted to about 1000 liters, and again filtered to remove further amounts of calcium sulphate therefrom. To the filtrate there is added about 225 kilos of common salt, and the whole is vigorouslystirred. The salt goes into solution and reacts with the calcium sulphonate with resulting formation of the sodium sulphonatewhieh separates in a solid form from the solution which contains the calcium in the term of calcium chloride. That is, the added common salt (sodium chloride) reacts with the calcium sulphonate in solution to form calcium chloride and the alkali sulphonate, and the alkali sulphonate so formed is then salted out or precipitated by the excess common salt, so that there is produced, as the result of the reaction, the precipitated sodium sulphonate, and a solution containing calcium chloride and the excess of'common salt. The sodium sulphonate is filtered out and washed with a strong common salt solution to free it from any calcium salts, and the sodium salt of benzene sulphonic acid is thus obbenzene-sulphonic tained in a state of sutiicient purity to adapt it for commercial use or for furthentreatmcnt.

2. 90 kilos of mono-chlor-benzene and 90 kilos of 66 B. sulphuric acid are stirred together vigorously and, to this mixture 0 there is added gradually about 180 kilos of fuming sulphuric acid containing about 26% free sulphur trioxide. This acid is added at such a rate that the temperature does not rise above 100 C. Heat is then applied to keep the temperature of the mixture at about 100 to 105 (3., until the odor of chlorbenzene is very slight, i. e., until the sul-* phonation has been practically completed. The sulphonation mixture thus produced and containing the excess of sulphuric acid, is diluted to about 1500 liters, heated to boiling, and treated with slaked lime until.

the solution 1s neutral or slightly alkaline to Congo paper. The precipitated calcium sulphate is filtered out and washed with water and the water added to the filtrate until the total volume of filtrate and washwater is about 2000 liters. The solution thus produced contains the calcium salt of the chlor-.

benzene-p-sulphoni'c acid. This solution is then treated to convert the calcium salt into.

the sodium salt and to bring about precipitation of the sodium salt. For this purpose, there is added an amount of common salt (sodium chloride) sufiicientfor this purpose. salt will bring about the se aration of a crystalline precipitate, but t e amount of this preci itate will" be materially increased by the a dition of still further. amounts of common salt, e. g., about 160 kilos more. After stirring for about one-half hour, the precipitate of the sodium salt-of the chloracid 1 is filtered off,

is then heated for'some time'to about 80 The addition of 320' kilos of common chloride washed with a 15% salt solution, and dried. The sodium salt is thus obtained as a dry crystalline solid, and is practically free from calcium salt.

3. Chlor-benzene is sub'ected to sulphonation for the production 0 the chlor-benzenep-sulphonic acid, according to example 2, but instead of isolating the chlor-benzenesulphonic acid in the form of its sodium salt, the sul honation mixture, without dilution and still containin the excess of conccntrated sulphuric acid: is subjected to nitration by the addition of mixed acid, i. e., a mixture of concentrated nitric and sulphuric acids, in appropriate amount for con verting the chlor-benzene-sulphohic acid in to the ortho-nitro-chlor-benzene-p-sulphonit acid. This nitration operation is carried out in the presence of the excess sulphuric acid which thus contributes tothe nitration and which is present at the end of the nitration. For example, phonation mixture )roduced according to ex ample 2, and coole to about 20 0., there is gradually run in about 174 kilos'of mixed acid containing 29% nitric acid, 65% sulphuric acid, and 6% water, and the temperature is kept between 30 and 50 C. Stirring is continued for some time after tendency to spontaneous heating ceases, and the reaction product, containing the excess acid, is then run into water with stirring, and thereby diluted with about five times its weight of water. solution of th nitro-chlor-benzene sulphonic acid still containing the excess sulphuric acid from the sulphonation, as well as that added for the nitration. then treated with slaked lime, not allowing the tem erature to rise above 40 -C., until it is exact 'y'neutral to Congo test paper, andt andthen filtered out to remove the calcium sulphate which 'is washed with hot water.

Or an excess 'of lime can be used for the hydrolysis will be avoided. The calcium' salt of the nitro-chlor-benz ene-sul honic acid is converted into the'sodium salt the addition or sufiicient sodium ehlori e to bring about the desired conv'ersion'of calcium'to sodium salt and the separation of the'sodium salt as a precipitate, 'for example, by adding common salt in the proportion of about 1 kilo 'to every 6 liters of the solution. The corresponding potassium and ammonium salts of the, nitro-chlor-benzene-sulphonie acid-may be similarly produced .by adding about 1 kilo of potassium or ammonium chloride, for every 10 liters of the above solution.

to the undiluted sul-- This solution is The conversion of the calcium salt in solution to the sodium salt is preferably carried out at room temperature or at a somewhat lower temperature owing to the increased solubility of the sodium salt in hot solutions, and the correspondingly less amount of salt required forprecipitation of In a companion application, Serial No.

' 355,157, filed January 30,1920, I have described and claimed an improved method of producing ortho-nitro-chlor-benzol-p-sul phonic acid and its salts, and I do not claim the same herein except in connection with the improved process of the present invention for roducing and isolating the alkali salts. T e process of said companion application is of more general application, and is not limited to the production and isolation of the alkali salts in the manner herein described and claimed; while the process of the present invention is likewise of more general application and is not limited to specific improvements in the sulphonation process itself, except in combination with the subsequent novel procedure for the production andisolation of the alkali sulphonates.

-I claim:

1. The method of converting soluble calcium salts of aromatic sulphonic acids into alkali salts of the'same acids, which comprises treating a solution of such calcium salts with an alkali chloride, the amount of the alkali chloride being sufiicient to bring about the conversion of the calcium sulphonate into the alkali sulphonate and the precipitation of the alkali sulphonate thus produced. a

2.,The methodof producing sodium salts of aromatic sulphonic acids, which comprises treatin a solution containing a calcium salt of t e sulphonic acid with sodium f chloride, whereby. the sodium salt of the sult of thesulthe alkali salt of the s phonic acid.

4. The method of producin alkali salts of chlor-substituted aromatic phonic acids, which comprises treating a solution containing a calcium salt of the chlorine substituted aromatic sulphonic acid with an alkali chloride, the amount of the alkali chloride being suflicient to react with the calcium salt by double decom osition and to form and precipitate the al ali salt of the sulphonic acid.

5. The method of producing alkali salts of nitro-substituted aromatic sulphonic acids, which comprises treating a solution containing a calcium salt of the nitro-substituted aromatic sulphonic acid with an alkali chloride, whereby the alkali salt of the nitro-substituted aromatic sulphonic acid is formed by double decomposition and pre- I cipitated out of the solutlon.

6. The method of producing sodium. salts of nitro-chlor-substituted aromatic sulphonic acids, which comprises treatin a solution containing a calcium salt of t e nitrochlor-substituted aromatic sulphonic acid with sodium chloride, whereby the sodium salt of the nitro-chlor-substituted aromatic sulphonic acid is formed by double decomposition and is precipitated out of the solution.

7. The method of converting solubleJcalcium salts of aromatic sulphonic acids of the benzene series into alkali salts of the same acids, which comprises treati a solution of such calcium salts with an a ali chloride, the amount of.,,the alkali chloride being sufficient to bring about the conversion of the i HOMER W. HILL R. 

